GianPaolo Marra, Institute of Atmospheric Sciences and Climate of the Italian National Research Council, LecceGiovanni Aloisio, Università di Lecce - Center for Advanced Computational Technologies/ISUFI Massimo Cafaro, Università di Lecce - Center for Advanced Computational Technologies/ISUFI D. Conte, Institute of Atmospheric Sciences and Climate of the Italian National Research Council, Lecce C. Elefante, Institute of Atmospheric Sciences and Climate of the Italian National Research Council, Lecce C. Mangia, Institute of Atmospheric Sciences and Climate of the Italian National Research Council, Lecce M. Miglietta, Institute of Atmospheric Sciences and Climate of the Italian National Research Council, Lecce U. Rizza, Institute of Atmospheric Sciences and Climate of the Italian National Research Council, Lecce I. Schipa, Institute of Atmospheric Sciences and Climate of the Italian National Research Council, Lecce G-AQFS (Grid Air Quality Forecast System): an experimental system based on GRID computing technologies to forecast atmospheric dispersion of pollutants